nl80211/mac80211: support full station state in AP mode

Today, stations are added already associated. That is
inefficient if, for example, the driver has no room
for stations any more because then the station will
go through the entire auth/assoc handshake, only to
be kicked out afterwards.

To address this a bit better, at least with drivers
using the new station state callback, allow hostapd
to add stations in unauthenticated mode, just after
receiving the AUTH frame, before even replying. Thus
if there's no more space at that point, it can send
a negative auth frame back. It still needs to handle
later state transition errors though, of course.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index b3cf7cc..087f68b 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3231,11 +3231,21 @@
 		/* accept only the listed bits */
 		if (params.sta_flags_mask &
 				~(BIT(NL80211_STA_FLAG_AUTHORIZED) |
+				  BIT(NL80211_STA_FLAG_AUTHENTICATED) |
+				  BIT(NL80211_STA_FLAG_ASSOCIATED) |
 				  BIT(NL80211_STA_FLAG_SHORT_PREAMBLE) |
 				  BIT(NL80211_STA_FLAG_WME) |
 				  BIT(NL80211_STA_FLAG_MFP)))
 			return -EINVAL;
 
+		/* but authenticated/associated only if driver handles it */
+		if (!(rdev->wiphy.features &
+				NL80211_FEATURE_FULL_AP_CLIENT_STATE) &&
+		    params.sta_flags_mask &
+				(BIT(NL80211_STA_FLAG_AUTHENTICATED) |
+				 BIT(NL80211_STA_FLAG_ASSOCIATED)))
+			return -EINVAL;
+
 		/* must be last in here for error handling */
 		params.vlan = get_vlan(info, rdev);
 		if (IS_ERR(params.vlan))
@@ -3393,17 +3403,31 @@
 		/* but don't bother the driver with it */
 		params.sta_flags_mask &= ~BIT(NL80211_STA_FLAG_TDLS_PEER);
 
+		/* allow authenticated/associated only if driver handles it */
+		if (!(rdev->wiphy.features &
+				NL80211_FEATURE_FULL_AP_CLIENT_STATE) &&
+		    params.sta_flags_mask &
+				(BIT(NL80211_STA_FLAG_AUTHENTICATED) |
+				 BIT(NL80211_STA_FLAG_ASSOCIATED)))
+			return -EINVAL;
+
 		/* must be last in here for error handling */
 		params.vlan = get_vlan(info, rdev);
 		if (IS_ERR(params.vlan))
 			return PTR_ERR(params.vlan);
 		break;
 	case NL80211_IFTYPE_MESH_POINT:
+		/* associated is disallowed */
+		if (params.sta_flags_mask & BIT(NL80211_STA_FLAG_ASSOCIATED))
+			return -EINVAL;
 		/* TDLS peers cannot be added */
 		if (params.sta_flags_set & BIT(NL80211_STA_FLAG_TDLS_PEER))
 			return -EINVAL;
 		break;
 	case NL80211_IFTYPE_STATION:
+		/* associated is disallowed */
+		if (params.sta_flags_mask & BIT(NL80211_STA_FLAG_ASSOCIATED))
+			return -EINVAL;
 		/* Only TDLS peers can be added */
 		if (!(params.sta_flags_set & BIT(NL80211_STA_FLAG_TDLS_PEER)))
 			return -EINVAL;